SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7e52adf74a0df24956dc71e9811a931538d021f4d8efe332e8c57d21aae41371' 
  AND token = 'i2eRPIjqO2OhiCHsWBCqb7wrg2ijnoneWkIFpph79OU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}